Morphinan Compounds

ABSTRACT

This disclosure relates to novel morphinan compounds and their derivatives, pharmaceutically acceptable salts, solvates, and hydrates thereof. This disclosure also provides compositions comprising a compound of this disclosure and the use of such compositions in methods of treating diseases and conditions that are beneficially treated by administering a σ 1  receptor agonist that also has NMDA antagonist activity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/334,227, filed Jul. 17, 2014, which is a continuation of U.S. patentapplication Ser. No. 14/141,694 (now U.S. Pat. No. 9,072,711), filedDec. 27, 2013, which is a continuation of U.S. patent application Ser.No. 13/949,499 (now U.S. Pat. No. 8,748,450), filed Jul. 24, 2013, whichis a continuation of U.S. patent application Ser. No. 13/118,935 (nowU.S. Pat. No. 8,541,436), filed May 31, 2011, which is a continuation ofU.S. patent application Ser. No. 12/112,936 (now U.S. Pat. No.7,973,049), filed Apr. 30, 2008, which claims the benefit of priorityunder 35 U.S.C. §119 to U.S. Provisional Application Ser. Nos.60/976,044, filed Sep. 28, 2007; 60/916,662, filed May 8,2007; and60/915,130, filed May 1,2007, the entire contents of which areincorporated by reference in their entirety herein.

BACKGROUND

This disclosure relates to novel morphinan compounds and theirderivatives, pharmaceutically acceptable salts, solvates, and hydratesthereof. This disclosure also provides compositions comprising acompound of this disclosure and the use of such compositions in methodsof treating diseases and conditions that are beneficially treated byadministering a σ₁ receptor agonist that also has NMDA antagonistactivity.

Dextromethorphan is currently one of the most widely used antitussives.Also known by the chemical name(+)-3-methoxy-17-methyl-(9α,13α,14α)-morphinan, dextromethorphan ismarketed as Zenvia® and Neurodex® in the form of a product comprisingdextromethorphan hydrobromide and quinidine sulfate.

In addition to the physiological activity noted above, dextromethorphanalso is an agonist of the σ₂ receptor, an N-methyl-D-aspartate (NDMA)antagonist, and an α3β4 nicotinic receptor antagonist. Dextromethorphaninhibits neurotransmitters, such as glutamate, from activating receptorsin the brain. Uptake of dopamine and serotonin are also inhibited.

Dextromethorphan is approved for use in over the counter coughsuppressant products. It is currently in Phase I clinical trials fortreating subjects with voice spasms, and Phase III clinical studies fortreating Rett Syndrome (http://www.clinicaltrials.gov). Dextromethorphanis being studied with other drugs in a Phase II clinical trialcharacterizing pain processing mechanisms in subjects with irritablebowel syndrome (http://www.clinicaltrials.gov/). Dextromethorphan isalso in Phase I clinical trials for treating hyperalgesia inmethadone-maintained subjects (http://www.clinicaltrials.gov/).

In addition, a combination of dextromethorphan hydrobromide andquinidine sulfate is currently in Phase III clinical trials for treatingdiabetic neuropathy pain. (http://www.clinicaltrials.gov). This drugcombination is also in Phase III clinical trials for treatingInvoluntary Emotional Expression Disorder (IEED), also known aspseudobulbar affect, in subjects suffering from Alzheimer's disease,stroke, Parkinson's disease and traumatic brain injury(http://www.clinicaltrials.gov).

Dextromethorphan is metabolized in the liver. Degradation begins with O-and N-demethylation to form primary metabolites dextrorphan and3-methoxy-morphinan, both of which are further N- and O-demethylatedrespectively to 3-hydroxy-morphinan. These three metabolites arebelieved to be therapeutically active. A major metabolic catalyst is thecytochrome P450 enzyme 2D6 (CPY2D6), which is responsible for theO-demethylation reactions of dextromethorphan and 3-methoxymorphinan.The N-demethylation dextromethorphan and dextrorphan are catalyzed byenzymes in the related CPY3A family. Conjugates of dextrorphan and3-hydroxymorphinan can be detected in human plasma and urine withinhours of ingestion.

Dextromethorphan abuse has been linked to its active metabolite,dextrorphan. The PCP-like effects attributed to dextromethorphan aremore reliably produced by dextrorphan and thus abuse potential in humansmay be attributable to dextromethorphan metabolism to dextrorphan.(Miller, S C et al., Addict Biol, 2005, 10(4): 325-7., Nicholson, K L etal., Psychopharmacology (Berl), 1999 Sep. 1, 146(1): 49-59., Pender, E Set al., Pediatr Emerg Care, 1991, 7: 163-7). One study on thepsychotropic effects of dextromethorphan found that extensivemetabolizers (EM's) reported a greater abuse potential compared to poormetabolizers (PM's) providing evidence that dextrorphan contributes todextromethorphan abuse potential (Zawertailo L A, et al., J ClinPsychopharmacol, 1998 August, 18(4): 332-7).

A significant fraction of the population has a functional deficiency inthe CYP2D6 enzyme. Thus, because the major metabolic pathway fordextromethorphan requires CYP2D6, the decreased activity results in muchgreater duration of action and greater drug effects in CYP2D6-deficientsubjects. In addition to intrinsic functional deficiency, certainmedications, such as antidepressants, are potent inhibitors of theCYP2D6 enzyme. With its slower metabolism in some people,dextromethorphan, especially in combination with other medication(s),can lead to serious adverse events.

A longer than recommended duration of a drug in the body may providecontinued beneficial effects, but it may also create or prolongundesired side effects. Undesirable side effects at recommended doses ofdextromethorphan therapy include nausea, loss of appetite, diarrhea,drowsiness, dizziness, and impotence.

Accordingly, it is desirable to provide a compound that has thebeneficial activities of dextromethorphan and may also have otherbenefits, e.g., reduced adverse side effects, with a decreased metabolicliability, to further extend its pharmacological effective life, enhancesubject compliance, and, potentially, to decrease populationpharmacokinetic variability and/or decrease its potential for dangerousdrug-drug interactions or decrease the likelihood of dextromethorphanabuse due to the formation of metabolities such as dextrorphan.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the stability over time of various compounds of thedisclosure in cynomolgus monkey liver microsomes.

FIG. 2 depicts the stability over time of various compounds of thedisclosure in human liver microsomes.

FIG. 3 depicts the stability over time of various compounds of thedisclosure in 2D6 Supersomes™.

FIG. 4 depicts plasma levels of Compound 101, dextromethorphan, as wellas deuterated dextrorphan isotopologues and dextrorphan, in monkeys inthe absence of quinidine co-dosing.

FIG. 5 depicts plasma levels of Compound 101, dextromethorphan, as wellas deuterated dextrorphan isotopologues and dextrorphan, in monkeysco-dosed with quinidine.

FIG. 6 depicts urine levels of Compound 101, dextromethorphan, as wellas deuterated dextrorphan isotopologues and dextrorphan, as a functionof quinidine concentration in monkeys

DETAILED DESCRIPTION Definitions

The terms “ameliorate” and “treat” are used interchangeably and includetherapeutic and/or prophylactic treatment. Both terms mean decrease,suppress, attenuate, diminish, arrest, or stabilize the development orprogression of a disease (e.g., a disease or disorder delineatedherein).

“Disease” means any condition or disorder that damages or interfereswith the normal function of a cell, tissue, or organ.

It will be recognized that some variation of natural isotopic abundanceoccurs in a synthesized compound depending upon the origin of chemicalmaterials used in the synthesis. Thus, a preparation of dextromethorphanwill inherently contain small amounts of deuterated and/or¹³C-containing isotopologues. The concentration of naturally abundantstable hydrogen and carbon isotopes, notwithstanding this variation, issmall and immaterial as compared to the degree of stable isotopicsubstitution of compounds of this disclosure. See, for instance, Wada Eet al, Seikagaku 1994, 66:15; Ganes L Z et al, Comp Biochem Physiol AMol Integr Physiol 1998, 119:725. In a compound of this disclosure, whena particular position is designated as having deuterium, it isunderstood that the abundance of deuterium at that position issubstantially greater than the natural abundance of deuterium, which is0.015%. A position designated as having deuterium typically has aminimum isotopic enrichment factor of at least 3000 (45% deuteriumincorporation) at each atom designated as deuterium in said compound.

The term “isotopic enrichment factor” as used herein means the ratiobetween the isotopic abundance and the natural abundance of a specifiedisotope.

In other embodiments, a compound of this disclosure has an isotopicenrichment factor for each designated deuterium atom of at least 3500(52.5% deuterium incorporation at each designated deuterium atom), atleast 4000 (60% deuterium incorporation), at least 4500 (67.5% deuteriumincorporation), at least 5000 (75% deuterium incorporation), at least5500 (82.5% deuterium incorporation), at least 6000 (90% deuteriumincorporation), at least 6333.3 (95% deuterium incorporation), at least6466.7 (97% deuterium incorporation), at least 6600 (99% deuteriumincorporation), or at least 6633.3 (99.5% deuterium incorporation).

In the compounds of this disclosure any atom not specifically designatedas a particular isotope is meant to represent any stable isotope of thatatom. Unless otherwise stated, when a position is designatedspecifically as “H” or “hydrogen”, the position is understood to havehydrogen at its natural abundance isotopic composition.

The term “isotopologue” refers to a species that has the same chemicalstructure and formula as a specific compound of this disclosure, withthe exception of the isotopic composition at one or more positions,e.g., H vs. D. Thus an isotopologue differs from a specific compound ofthis disclosure in the isotopic composition thereof.

The term “compound,” as used herein, is also intended to include anysalts, solvates or hydrates thereof.

A salt of a compound of this disclosure is formed between an acid and abasic group of the compound, such as an amino functional group, or abase and an acidic group of the compound, such as a carboxyl functionalgroup. According to another embodiment, the compound is apharmaceutically acceptable acid addition salt.

The term “pharmaceutically acceptable,” as used herein, refers to acomponent that is, within the scope of sound medical judgment, suitablefor use in contact with the tissues of humans and other mammals withoutundue toxicity, irritation, allergic response and the like, and arecommensurate with a reasonable benefit/risk ratio. A “pharmaceuticallyacceptable salt” means any non-toxic salt that, upon administration to arecipient, is capable of providing, either directly or indirectly, acompound of this disclosure. A “pharmaceutically acceptable counterion”is an ionic portion of a salt that is not toxic when released from thesalt upon administration to a recipient.

Acids commonly employed to form pharmaceutically acceptable saltsinclude inorganic acids such as hydrogen bisulfide, hydrochloric acid,hydrobromic acid, hydroiodic acid, sulfuric acid and phosphoric acid, aswell as organic acids such as para-toluenesulfonic acid, salicylic acid,tartaric acid, bitartaric acid, ascorbic acid, maleic acid, besylicacid, fumaric acid, gluconic acid, glucuronic acid, formic acid,glutamic acid, methanesulfonic acid, ethanesulfonic acid,benzenesulfonic acid, lactic acid, oxalic acid, para-bromophenylsulfonicacid, carbonic acid, succinic acid, citric acid, benzoic acid and aceticacid, as well as related inorganic and organic acids. Suchpharmaceutically acceptable salts thus include sulfate, pyrosulfate,bisulfate, sulfite, bisulfite, phosphate, monohydrogenphosphate,dihydrogenphosphate, metaphosphate, pyrophosphate, chloride, bromide,iodide, acetate, propionate, decanoate, caprylate, acrylate, formate,isobutyrate, caprate, heptanoate, propiolate, oxalate, malonate,succinate, suberate, sebacate, fumarate, maleate, butyne-1,4-dioate,hexyne-1,6-dioate, benzoate, chlorobenzoate, methylbenzoate,dinitrobenzoate, hydroxybenzoate, methoxybenzoate, phthalate,terephthalate, sulfonate, xylene sulfonate, phenylacetate,phenylpropionate, phenylbutyrate, citrate, lactate, β-hydroxybutyrate,glycolate, maleate, tartrate, methanesulfonate, propanesulfonate,naphthalene-1-sulfonate, naphthalene-2-sulfonate, mandelate and othersalts. In one embodiment, pharmaceutically acceptable acid additionsalts include those formed with mineral acids such as hydrochloric acidand hydrobromic acid, and especially those formed with organic acidssuch as maleic acid.

As used herein, the term “hydrate” means a compound which furtherincludes a stoichiometric or non-stoichiometric amount of water bound bynon-covalent intermolecular forces.

As used herein, the term “solvate” means a compound which furtherincludes a stoichiometric or non-stoichiometric amount of solvent suchas water, acetone, ethanol, methanol, dichloromethane, 2-propanol, orthe like, bound by non-covalent intermolecular forces.

The compounds of the present disclosure (e.g., compounds of Formula I),may contain an asymmetric carbon atom, for example, as the result ofdeuterium substitution or otherwise. As such, compounds of thisdisclosure can exist as either individual enantiomers, or mixtures ofthe two enantiomers. Accordingly, a compound of the present disclosurewill include both racemic mixtures, and also individual respectivestereoisomers that are substantially free from another possiblestereoisomer. The term “substantially free of other stereoisomers” asused herein means less than 25% of other stereoisomers, preferably lessthan 10% of other stereoisomers, more preferably less than 5% of otherstereoisomers and most preferably less than 2% of other stereoisomers,or less than “X”% of other stereoisomers (wherein X is a number between0 and 100, inclusive) are present. Methods of obtaining or synthesizingan individual enantiomer for a given compound are well known in the artand may be applied as practicable to final compounds or to startingmaterial or intermediates.

The term “stable compounds,” as used herein, refers to compounds whichpossess stability sufficient to allow for their manufacture and whichmaintain the integrity of the compound for a sufficient period of timeto be useful for the purposes detailed herein (e.g., formulation intotherapeutic products, intermediates for use in production of therapeuticcompounds, isolatable or storable intermediate compounds, treating adisease or condition responsive to therapeutic agents).

“D” refers to deuterium.

“Stereoisomer” refers to both enantiomers and diastereomers.

Throughout this specification, a variable may be referred to generally(e.g., “each R”) or may be referred to specifically (e.g., R¹ or R²).Unless otherwise indicated, when a variable is referred to generally, itis meant to include all specific embodiments of that particularvariable.

Therapeutic Compounds

The present disclosure provides a compound of Formula I, includingpharmaceutically acceptable salts, solvates, and hydrates thereof:

wherein

R¹ is selected from CH₃, CH₂D, CHD₂, CD₃, CHF₂, and CF₃; and

R² is selected from CH₃, CH₂D, CHD₂, and CD₃.

In certain embodiments, when R¹ is CH₃, then R² is not CH₃ or CD₃. Inother embodiments, when R¹ is CD₃, then R² is not CH₃.

In one embodiment, R¹ is selected from CH₂D, CHD₂, CD₃, CHF₂, and CF₃.In another embodiment, R¹ is selected from CH₂D, CHD₂, and CD₃. In afurther embodiment, R¹ is CD₃. In another embodiment, R¹ is CF₃. In afurther embodiment, R¹ is CHF₂.

In one embodiment, R² is CH₃, CHD₂ or CD₃. In another embodiment, R² isCH₃. In another embodiment, R² is CD₃.

In yet another embodiment, the compound is selected from any one of thecompounds set forth in Table 1.

TABLE 1 Exemplary Compounds of Formula I Compound No. R¹ R² 100 CD₃ CH₃101 CD₃ CD₃ 102 CD₂H CD₃ 103 CD₃ CD₂H 104 CF3 CH₃ 105 CF₃ CD₃ 106 CHF₂CH₃ 107 CHF₂ CD₃ 108 CH₃ CD₃

In another set of embodiments, any atom not designated as deuterium inany of the embodiments set forth above is present at its naturalisotopic abundance. [41] In another set of embodiments, the compound ofFormula I is isolated or purified, e.g., the compound of Formula I ispresent at a purity of at least 50% by weight (e.g., at least 55%, 60%,65%, 70%, 75%, 80%, 85%, 90%, 95%, 97%, 98%, 98.5%, 99%, 99.5% or 99.9%)of the total amount of isotopologues of Formula I present, respectively.Thus, in some embodiments, a composition comprising a compound ofFormula I can include a distribution of isotopologues of the compound,provided at least 50% of the isotopologues by weight are the recitedcompound.

In some embodiments, any position in the compound of Formula Idesignated as having D has a minimum deuterium incorporation of at least45% (e.g., at least 52.5%, at least 60%, at least 67.5%, at least 75%,at least 82.5%, at least 90%, at least 95%, at least 97%, at least 99%,or at least 99.5%) at the designated position(s) of the compound ofFormula I. Thus, in some embodiments, a composition comprising acompound of Formula I can include a distribution of isotopologues of thecompound, provided at least 45% of the isotopologues include a D at thedesignated position(s).

In some embodiments, a compound of Formula I is “substantially free of”other isotopologues of the compound, e.g., less than 50%, less than 25%,less than 10%, less than 5%, less than 2%, less than 1%, or less than0.5% of other isotopologues are present.

The synthesis of compounds of Formula I can be readily achieved bysynthetic chemists of ordinary skill. Relevant procedures andintermediates are disclosed, for instance in Kim H C et al., Bioorg MedChem Lett 2001, 11:1651 and Newman A H etal., J Med Chem 1992, 35:4135.

Such methods can be carried out utilizing corresponding deuterated andoptionally, other isotope-containing reagents and/or intermediates tosynthesize the compounds delineated herein, or invoking standardsynthetic protocols known in the art for introducing isotopic atoms to achemical structure.

Exemplary Synthesis

A convenient method for synthesizing compounds of Formula I substitutesthe appropriate deuterated intermediates and reagents in synthesismethods utilized for the preparation of dextromethorphan. Compounds ofFormula I may be prepared from one of the known intermediates X, XI, andXII shown below, and from related intermediates that may be readilyobtained from known procedures.

Scheme 1 shows a general route to the compounds of Formula I.

Scheme 1 shows a general route for preparing compounds of Formula Iwherein R¹ is not CH₃. The HBr salt, 10, after treatment with NH₄OH, isN-demethylated to yield 11. Acylation of the amine 11 using theethylchloroformate provides the carbamate 12 which is thenO-demethylated using BBr₃ to yield the alcohol 13. Compound 13 istreated, in the presence of base, with an appropriately deuteratediodomethane to yield the ether 14, which is reduced using either lithiumaluminum deuteride (LAD) to yield compounds of Formula I wherein R²═CD₃or lithium aluminum hydride (LAH) to yield compounds of Formula Iwherein R²═CH₃. For those compounds of Formula I wherein R¹ is CH₃,carbamate 12 is directly treated with LAD to produce a compound where R²is CD₃.

Various R¹ groups (as defined in Formula I) may be introduced byO-alkylation of the appropriate phenol intermediate using anR¹-alkylating agent, such as an alkyl halide (for example, iodo-R¹),according to methods generally known in the art. Various R² groups (asdefined in Formula I) may be introduced by N-alkylation using anR²-alkylating agent (for example, iodo-R²), or by reduction of theN-formyl group with a deuterated reagent, such as deuteroboraneaccording to methods generally known in the art.

The specific approaches and compounds shown above are not intended to belimiting. The chemical structures in the schemes herein depict variablesthat are hereby defined commensurately with chemical group definitions(moieties, atoms, etc.) of the corresponding position in the compoundformulae herein, whether identified by the same variable name (i.e., R¹or R²) or not. The suitability of a chemical group in a compoundstructure for use in the synthesis of another compound is within theknowledge of one of ordinary skill in the art.

Additional methods of synthesizing compounds of Formula I and theirsynthetic precursors, including those within routes not explicitly shownin schemes herein, are within the means of chemists of ordinary skill inthe art. Synthetic chemistry transformations and protecting groupmethodologies (protection and deprotection) useful in synthesizing theapplicable compounds are known in the art and include, for example,those described in Larock R, Comprehensive Organic Transformations, VCHPublishers (1989); Greene T W et al., Protective Groups in OrganicSynthesis, 3^(rd) Ed., John Wiley and Sons (1999); Fieser L et al.,Fieser and Fieser's Reagents for Organic Synthesis, John Wiley and Sons(1994); and Paquette L, ed., Encyclopedia of Reagents for OrganicSynthesis, John Wiley and Sons (1995) and subsequent editions thereof.

Combinations of substituents and variables envisioned by this disclosureare only those that result in the formation of stable compounds.

Compositions

The disclosure also provides pyrogen-free compositions comprising aneffective amount of a compound of Formula I (e.g., including any of theformulae herein), or a pharmaceutically acceptable salt, solvate, orhydrate of said compound; and an acceptable carrier. Preferably, acomposition of this disclosure is formulated for pharmaceutical use (“apharmaceutical composition”), wherein the carrier is a pharmaceuticallyacceptable carrier. The carrier(s) are “acceptable” in the sense ofbeing compatible with the other ingredients of the formulation and, inthe case of a pharmaceutically acceptable carrier, not deleterious tothe recipient thereof in an amount used in the medicament.

Pharmaceutically acceptable carriers, adjuvants and vehicles that may beused in the pharmaceutical compositions of this disclosure include, butare not limited to, ion exchangers, alumina, aluminum stearate,lecithin, serum proteins, such as human serum albumin, buffer substancessuch as phosphates, glycine, sorbic acid, potassium sorbate, partialglyceride mixtures of saturated vegetable fatty acids, water, salts orelectrolytes, such as protamine sulfate, disodium hydrogen phosphate,potassium hydrogen phosphate, sodium chloride, zinc salts, colloidalsilica, magnesium trisilicate, polyvinyl pyrrolidone, cellulose-basedsubstances, polyethylene glycol, sodium carboxymethylcellulose,polyacrylates, waxes, polyethylene-polyoxypropylene-block polymers,polyethylene glycol and wool fat.

If required, the solubility and bioavailability of the compounds of thepresent disclosure in pharmaceutical compositions may be enhanced bymethods well-known in the art. One method includes the use of lipidexcipients in the formulation. See “Oral Lipid-Based Formulations:Enhancing the Bioavailability of Poorly Water-Soluble Drugs (Drugs andthe Pharmaceutical Sciences),” David J. Hauss, ed. Informa Healthcare,2007; and “Role of Lipid Excipients in Modifying Oral and ParenteralDrug Delivery: Basic Principles and Biological Examples,” Kishor M.Wasan, ed. Wiley-Interscience, 2006.

Another known method of enhancing bioavailability is the use of anamorphous form of a compound of this disclosure optionally formulatedwith a poloxamer, such as LUTROL™ and PLUIRONIC™ (BASF Corporation), orblock copolymers of ethylene oxide and propylene oxide. See U.S. Pat.No. 7,014,866; and United States patent publications 2006/0094744 and2006/0079502.

The pharmaceutical compositions of the disclosure include those suitablefor oral, rectal, nasal, topical (including buccal and sublingual),vaginal or parenteral (including subcutaneous, intramuscular,intravenous and intradermal) administration. In certain embodiments, thecompound of the formulae herein is administered transdermally (e.g.,using a transdermal patch or iontophoretic techniques). Otherformulations may conveniently be presented in unit dosage form, e.g.,tablets, sustained release capsules, and in liposomes, and may beprepared by any methods well known in the art of pharmacy. See, forexample, Remington's Pharmaceutical Sciences, Mack Publishing Company,Philadelphia, Pa. (17th ed. 1985).

Such preparative methods include the step of bringing into associationwith the molecule to be administered ingredients such as the carrierthat constitutes one or more accessory ingredients. In general, thecompositions are prepared by uniformly and intimately bringing intoassociation the active ingredients with liquid carriers, liposomes orfinely divided solid carriers, or both, and then, if necessary, shapingthe product.

In certain embodiments, the compound is administered orally.Compositions of the present disclosure suitable for oral administrationmay be presented as discrete units such as capsules, sachets, or tabletseach containing a predetermined amount of the active ingredient; apowder or granules; a solution or a suspension in an aqueous liquid or anon-aqueous liquid; an oil-in-water liquid emulsion; a water-in-oilliquid emulsion; packed in liposomes; or as a bolus, etc. Soft gelatincapsules can be useful for containing such suspensions, which maybeneficially increase the rate of compound absorption.

In the case of tablets for oral use, carriers that are commonly usedinclude lactose and corn starch. Lubricating agents, such as magnesiumstearate, are also typically added. For oral administration in a capsuleform, useful diluents include lactose and dried cornstarch. When aqueoussuspensions are administered orally, the active ingredient is combinedwith emulsifying and suspending agents. If desired, certain sweeteningand/or flavoring and/or coloring agents may be added.

Compositions suitable for oral administration include lozengescomprising the ingredients in a flavored basis, usually sucrose andacacia or tragacanth; and pastilles comprising the active ingredient inan inert basis such as gelatin and glycerin, or sucrose and acacia.

Compositions suitable for parenteral administration include aqueous andnon-aqueous sterile injection solutions which may contain anti-oxidants,buffers, bacteriostats and solutes which render the formulation isotonicwith the blood of the intended recipient; and aqueous and non-aqueoussterile suspensions which may include suspending agents and thickeningagents. The formulations may be presented in unit-dose or multi-dosecontainers, for example, sealed ampules and vials, and may be stored ina freeze dried (lyophilized) condition requiring only the addition ofthe sterile liquid carrier, for example water for injections,immediately prior to use. Extemporaneous injection solutions andsuspensions may be prepared from sterile powders, granules and tablets.

Such injection solutions may be in the form, for example, of a sterileinjectable aqueous or oleaginous suspension. This suspension may beformulated according to techniques known in the art using suitabledispersing or wetting agents (such as, for example, Tween 80) andsuspending agents. The sterile injectable preparation may also be asterile injectable solution or suspension in a non-toxicparenterally-acceptable diluent or solvent, for example, as a solutionin 1,3-butanediol. Among the acceptable vehicles and solvents that maybe employed are mannitol, water, Ringer's solution and isotonic sodiumchloride solution. In addition, sterile, fixed oils are conventionallyemployed as a solvent or suspending medium. For this purpose, any blandfixed oil may be employed including synthetic mono- or diglycerides.Fatty acids, such as oleic acid and its glyceride derivatives are usefulin the preparation of injectables, as are naturalpharmaceutically-acceptable oils, such as olive oil or castor oil,especially in their polyoxyethylated versions. These oil solutions orsuspensions may also contain a long-chain alcohol diluent or dispersant.

The pharmaceutical compositions of this disclosure may be administeredin the form of suppositories for rectal administration. Thesecompositions can be prepared by mixing a compound of this disclosurewith a suitable non-irritating excipient which is solid at roomtemperature but liquid at the rectal temperature and therefore will meltin the rectum to release the active components. Such materials include,but are not limited to, cocoa butter, beeswax and polyethylene glycols.

The pharmaceutical compositions of this disclosure may be administeredby nasal aerosol or inhalation. Such compositions are prepared accordingto techniques well-known in the art of pharmaceutical formulation andmay be prepared as solutions in saline, employing benzyl alcohol orother suitable preservatives, absorption promoters to enhancebioavailability, fluorocarbons, and/or other solubilizing or dispersingagents known in the art. See, e.g.: Rabinowitz J D and Zaffaroni A C,U.S. Pat. No. 6,803,031, assigned to Alexza Molecular DeliveryCorporation.

Topical administration of the pharmaceutical compositions of thisdisclosure is especially useful when the desired treatment involvesareas or organs readily accessible by topical application. For topicalapplication topically to the skin, the pharmaceutical composition shouldbe formulated with a suitable ointment containing the active componentssuspended or dissolved in a carrier. Carriers for topical administrationof the compounds of this disclosure include, but are not limited to,mineral oil, liquid petroleum, white petroleum, propylene glycol,polyoxyethylene polyoxypropylene compound, emulsifying wax, and water.Alternatively, the pharmaceutical composition can be formulated with asuitable lotion or cream containing the active compound suspended ordissolved in a carrier. Suitable carriers include, but are not limitedto, mineral oil, sorbitan monostearate, polysorbate 60, cetyl esterswax, cetearyl alcohol, 2-octyldodecanol, benzyl alcohol, and water. Thepharmaceutical compositions of this disclosure may also be topicallyapplied to the lower intestinal tract by rectal suppository formulationor in a suitable enema formulation. Topically-transdermal patches andiontophoretic administration are also included in this disclosure.

Application of the subject therapeutics may be local, so as to beadministered at the site of interest. Various techniques can be used forproviding the subject compositions at the site of interest, such asinjection, use of catheters, trocars, projectiles, pluronic gel, stents,sustained drug release polymers or other device which provides forinternal access.

Thus, according to yet another embodiment, the compounds of thisdisclosure may be incorporated into compositions for coating animplantable medical device, such as prostheses, artificial valves,vascular grafts, stents, or catheters. Suitable coatings and the generalpreparation of coated implantable devices are known in the art and areexemplified in U.S. Pat. Nos. 6,099,562; 5,886,026; and 5,304,121. Thecoatings are typically biocompatible polymeric materials such as ahydrogel polymer, polymethyldisiloxane, polycaprolactone, polyethyleneglycol, polylactic acid, ethylene vinyl acetate, and mixtures thereofThe coatings may optionally be further covered by a suitable topcoat offluorosilicone, polysaccharides, polyethylene glycol, phospholipids orcombinations thereof to impart controlled release characteristics in thecomposition. Coatings for invasive devices are to be included within thedefinition of pharmaceutically acceptable carrier, adjuvant or vehicle,as those terms are used herein.

According to another embodiment, the disclosure provides a method ofcoating an implantable medical device comprising the step of contactingsaid device with the coating composition described above. It will beobvious to those skilled in the art that the coating of the device willoccur prior to implantation into a mammal.

According to another embodiment, the disclosure provides a method ofimpregnating an implantable drug release device comprising the step ofcontacting said drug release device with a compound or composition ofthis disclosure. Implantable drug release devices include, but are notlimited to, biodegradable polymer capsules or bullets, non-degradable,diffusible polymer capsules and biodegradable polymer wafers.

According to another embodiment, the disclosure provides an implantablemedical device coated with a compound or a composition comprising acompound of this disclosure, such that said compound is therapeuticallyactive.

According to another embodiment, the disclosure provides an implantabledrug release device impregnated with or containing a compound or acomposition comprising a compound of this disclosure, such that saidcompound is released from said device and is therapeutically active.

Where an organ or tissue is accessible because of removal from thesubject, such organ or tissue may be bathed in a medium containing acomposition of this disclosure, a composition of this disclosure may bepainted onto the organ, or a composition of this disclosure may beapplied in any other convenient way.

In another embodiment, a composition of this disclosure furthercomprises a second therapeutic agent. The second therapeutic agent maybe selected from any compound or therapeutic agent known to have or thatdemonstrates advantageous properties when administered with a compoundhaving the same mechanism of action as dextromethorphan. Such agentsinclude those indicated as being useful in combination withdextromethorphan, including but not limited to, those described in U.S.Pat. Nos. 4,316,888; 4,446,140; 4,694,010; 4,898,860; 5,166,207;5,336,980; 5,350,756; 5,366,980; 5,863,927; RE38,115; 6,197,830;6,207,164; 6,583,152; and 7,114,547; as well as in US patentpublications 2001/0044446; 2002/0103109; 2004/0087479; 2005/0129783;2005/0203125; and 2007/0191411.

Preferably, the second therapeutic agent is an agent useful in thetreatment or prevention of a disease or condition selected fromemotional lability; pseudobulbar affect; autism; neurological disordersand neurodegenerative diseases, such as, e.g., dementia, amyotrophiclateral sclerosis (ALS, also known as Leu Gehrig's disease), Alzheimer'sdisease, Parkinson's disease, and multiple sclerosis; disturbances ofconsciousness disorders; brain injuries, such as, e.g., stroke,traumatic brain injury, ischemic event, hypoxic event and neuronaldeath; disturbances of consciousness disorders; cardiovascular diseases,such as, e.g., peripheral vascular diseases, myocardial infarctions, andatherosclerosis; glaucoma, tardive dyskinesia; diabetic neuropathy;retinopathic diseases; diseases or disorders caused byhomocysteine-induced apoptosis; diseases or disorders caused by elevatedlevels of homocysteine; chronic pain; intractable pain; neuropathicpain, sympathetically mediated pain, such as, allodynia, hyperpathia,hyperalgesia, dysesthesia, paresthesia, deafferentation pain, andanesthesia dolorosa pain; pain associated with gastrointestinaldysfunction, including, e.g., irritable bowel syndrome; mouth pain;epileptic seizures; tinnitus; sexual dysfunction; intractable coughing;dermatitis; addiction disorders, such as, e.g., addiction to ordependence on stimulants, nicotine, morphine, heroine, other opiates,amphetamines, cocaine, and alcohol; Rett syndrome (RTT); voice disordersdue to uncontrolled laryngeal muscle spasms, including e.g., abductorspasmodic dysphonia, adductor spasmodic dysphonia, muscular tensiondysphonia, and vocal tremor; methotrexate neurotoxicity; and fatiguecaused by cancer.

In one embodiment, the second therapeutic agent is selected fromquinidine, quinidine sulfate, LBH589 (Novartis), oxycodone, andgabapentin.

In another embodiment, the disclosure provides separate dosage forms ofa compound of this disclosure and one or more of any of theabove-described second therapeutic agents, wherein the compound andsecond therapeutic agent are associated with one another. The term“associated with one another” as used herein means that the separatedosage forms are packaged together or otherwise attached to one anothersuch that it is readily apparent that the separate dosage forms areintended to be sold and administered together (within less than 24 hoursof one another, consecutively or simultaneously).

In the pharmaceutical compositions of the disclosure, the compound ofthe present disclosure is present in an effective amount. As usedherein, the term “effective amount” refers to an amount which, whenadministered in a proper dosing regimen, is sufficient to reduce orameliorate the severity, duration or progression of the disorder beingtreated, prevent the advancement of the disorder being treated, causethe regression of the disorder being treated, or enhance or improve theprophylactic or therapeutic effect(s) of another therapy.

The interrelationship of dosages for animals and humans (based onmilligrams per meter squared of body surface) is described in Freireichet al., (1966) Cancer Chemother. Rep 50: 219. Body surface area may beapproximately determined from height and weight of the subject. See,e.g., Scientific Tables, Geigy Pharmaceuticals, Ardsley, N.Y., 1970,537.

In one embodiment, an effective amount of a compound of this disclosurecan range from 0.4 mg to 400 mg, from 4.0 mg to 350 mg, from 10 mg to 90mg, or from 30 mg to 45 mg, inclusive.

Effective doses will also vary, as recognized by those skilled in theart, depending on the diseases treated, the severity of the disease, theroute of administration, the sex, age and general health condition ofthe subject, excipient usage, the possibility of co-usage with othertherapeutic treatments such as use of other agents and the judgment ofthe treating physician. For example, guidance for selecting an effectivedose can be determined by reference to the prescribing information fordextromethorphan.

The compounds of the present disclosure and the pharmaceuticalcompositions that comprise them demonstrate a longer clearance andproduce a higher plasma exposure level 12 hours post-dosing as comparedto a pharmaceutical composition comprising the same amount ofdextromethorphan on a mole basis (“molar equivalent dextromethorphancomposition”). Thus, in one embodiment, the disclosure provides apharmaceutical composition comprising an effective amount of a compoundof Formula I, the administration of which to a subject results in aplasma exposure level that is greater than the plasma exposure level ofa molar equivalent dextromethorphan composition that is administeredusing the same dosing regimen.

In another embodiments, the plasma exposure level is at least 110%,115%, 120% 125%, 130%, 135%, 140%, 145%, or more of the plasma exposurelevel of dextromethorphan produced by a molar equivalentdextromethorphan composition that is administered to an equivalentsubject.

In another embodiment, the disclosure provides a pharmaceuticalcomposition comprising 10-60 mg of a compound of Formula I, wherein theadministration of the pharmaceutical composition to a subject results ina plasma exposure level in the range of 250-750 nanograms (ng)-hour(h)/mL (AUC).

In another embodiment, the disclosure provides a pharmaceuticalcomposition comprising 10-60 mg of a compound of Formula I, wherein theadministration of the pharmaceutical composition to a subject results ina plasma exposure level in the range of 400-1600 ng-h/mL (AUC).

In another embodiment, the disclosure provides a pharmaceuticalcomposition comprising 10-60 mg of a compound of Formula I, wherein theadministration of the pharmaceutical composition to a subject results ina plasma exposure level in the range of 500-1500 ng-h/mL (AUC).

In another embodiment, the disclosure provides a pharmaceuticalcomposition comprising 10-60 mg of a compound of Formula I, wherein theadministration of the pharmaceutical composition to a subject results ina plasma exposure level in the range of 1000-1500 ng-h/mL (AUC).

In another embodiment, the disclosure provides a pharmaceuticalcomposition comprising an effective amount of a compound of Formula I,the administration of which to a subject results in a decrease in rateand amount of metabolite production as compared to a molar equivalentdextromethorphan composition that is administered using the same dosingregimen.

In another embodiment, the disclosure provides a pharmaceuticalcomposition comprising 10-60 mg of a compound of Formula I, theadministration of which to a subject results in a plasma exposure levelof deuterated dextrorphan isotopologues less than or equal to 1000ng-h/mL.

In another embodiment, the disclosure provides a pharmaceuticalcomposition comprising 10-60 mg of a compound of Formula I, theadministration of which to a subject results in a plasma exposure levelof deuterated dextrorphan isotopologues less than or equal to 750ng-h/mL.

In another embodiment, the disclosure provides a pharmaceuticalcomposition comprising 10-60 mg of a compound of Formula I, theadministration of which to a subject results in a plasma exposure levelof deuterated dextrorphan isotopologues less than or equal to 500ng-h/mL.

In another embodiment, the disclosure provides a pharmaceuticalcomposition comprising an effective amount of a compound of Formula I,the administration of which to a subject results in both an increase inthe plasma exposure level of a compound of Formula I and a decrease inthe plasma exposure level of dextromethorphan metabolite isotopologues,particularly deuterated dextrorphan isotopologues, as compared to theplasma exposure levels of dextromethorphan and dextrorphan produced froma molar equivalent dextromethorphan composition that is administered inthe same dosing regimen.

In another embodiment, the disclosure provides a pharmaceuticalcomposition comprising 10-60 mg of a compound of Formula I, saidcomposition providing a plasma exposure level of a compound of Formula Iof from about 1750 to about 250 ng-h/mL after repeated administration toa subject every 12 hours through steady-state conditions.

For pharmaceutical compositions that comprise a second therapeuticagent, an effective amount of the second therapeutic agent is betweenabout 0.01% to 100% of the dosage normally utilized in a monotherapyregime using just that agent. The normal monotherapeutic dosages ofthese second therapeutic agents are well known in the art. See, e.g.,Wells et al., eds., Pharmacotherapy Handbook, 2nd Edition, Appleton andLange, Stamford, Conn. (2000); PDR Pharmacopoeia, Tarascon PocketPharmacopoeia 2000, Deluxe Edition, Tarascon Publishing, Loma Linda,Calif. (2000), each of which are incorporated herein by reference intheir entirety.

It is expected that some of the second therapeutic agents referencedabove will act synergistically with the compounds of this disclosure.When this occurs, it will allow the effective dosage of the secondtherapeutic agent and/or the compound of this disclosure to be reducedfrom that required in a monotherapy. This has the advantage ofminimizing toxic side effects of either the second therapeutic agent ofa compound of this disclosure, synergistic improvements in efficacy,improved ease of administration or use and/or reduced overall expense ofcompound preparation or formulation.

Thus, in one embodiment, the disclosure provides a pharmaceuticalcomposition comprising 10-60 mg of a compound of Formula I and 2.5-30 mgquinidine, said composition providing a maximum plasma exposure levelafter repeated administration every 12 to 24 hours through steady-stateconditions of a compound of Formula I in a subject of from about 1750 toabout 250 ng-h/mL, wherein the administration of said composition to asubject results in a reduction in the plasma exposure level ofdeuterated dextrorphan isotopologues as compared to the same molaramount of a compound of Formula I administered without the quinidine.

In another embodiment, the disclosure provides a pharmaceuticalcomposition comprising 10-60 mg of a compound of Formula I and 2.5-20 mgquinidine, said composition providing a maximum plasma exposure levelafter repeated administration every 12 to 24 hours through steady-stateconditions of a compound of Formula I in a subject of from about 1750 toabout 250 ng-h/mL, wherein the administration of said composition to asubject results in a reduction in the plasma exposure level ofdeuterated dextrorphan isotopologues as compared to the same molaramount of a compound of Formula I administered without the quinidine.

In another embodiment, the disclosure provides a pharmaceuticalcomposition comprising 10-60 mg of a compound of Formula I and 2.5-10 mgquinidine, said composition providing a maximum plasma exposure levelafter repeated administration every 12 to 24 hours through steady-stateconditions of a compound of Formula I in a subject of from about 1750 toabout 250 ng-h/mL, wherein the administration of said composition to asubject results in a reduction in the plasma exposure level ofdeuterated dextrorphan isotopologues as compared to the same molaramount of a compound of Formula I administered without the quinidine.

In another embodiment, the disclosure provides a pharmaceuticalcomposition comprising a 15-45 mg of a compound of Formula I and 2.5-30mg quinidine, said composition providing a maximum plasma exposure levelafter repeated administration every 12 to 24 hours through steady-stateconditions of a compound of Formula Tin a subject of from about 1750 toabout 250 ng-h/mL, wherein the administration of said composition to asubject results in a reduction in the plasma exposure level ofdeuterated dextrorphan isotopologues as compared to the same molaramount of a compound of Formula I administered without the quinidine.

In another embodiment, the disclosure provides a pharmaceuticalcomposition comprising a 20-35 mg of a compound of Formula I and 2.5-30mg quinidine, said composition providing a maximum plasma exposure levelafter repeated administration every 12 to 24 hours through steady-stateconditions of a compound of Formula Tin a subject of from about 1750 toabout 250 ng-h/mL, wherein the administration of said composition to asubject results in a reduction in the plasma exposure level ofdeuterated dextrorphan isotopologues as compared to the same molaramount of a compound of Formula I administered without the quinidine.

In another embodiment, the disclosure provides a pharmaceuticalcomposition comprising a compound of Formula I and quinidine, saidcomposition providing lower urine concentrations of a compound ofFormula I and higher urine concentrations of deuterated dextrorphanisotopologues in a subject as compared to urine concentrations ofdextromethorphan and dextrorphan in an equivalent subject resulting fromthe administration of a molar equivalent dextromethorphan compositionadditionally comprising the same amount of quinidine and administeredaccording to the same dosing regimen.

Methods of Treatment

In another embodiment, the disclosure provides a method of modulatingthe activity of the σ₂ receptor, N-methyl-D-aspartate (NDMA), or theactivity of the α3β4 nicotinic receptor in a cell, comprising contactinga cell with one or more compounds of Formula I.

In another embodiment, the disclosure provides a method of inhibitingneurotransmitters, such as glutamate, from activating receptors in thebrain and/or inhibiting the uptake of dopamine and serotonin byadministering a compound of Formula I.

According to another embodiment, the disclosure provides a method oftreating a subject suffering from, or susceptible to, a disease that isbeneficially treated by dextromethorphan comprising the step ofadministering to said subject an effective amount of a compound ofFormula I wherein R¹ is selected from CH₃, CH₂D, CHD₂, CD₃, CHF₂, andCF₃; and R² is selected from CH₃, CH₂D, CHD₂, and CD₃ or a compositioncomprising such a compound. Such diseases are well known in the art andare disclosed in, but not limited to, those described in U.S. Pat. Nos.4,316,888; 4,446,140; 4,694,010; 4,898,860; 5,166,207; 5,336,980;5,350,756; 5,366,980; 5,863,927; RE38,115; 6,197,830; 6,207,164;6,583,152; and 7,114,547; as well as in US patent publications2001/0044446; 2002/0103109; 2004/0087479; 2005/0129783; 2005/0203125;and 2007/0191411.

Such diseases include, but are not limited to, emotional lability;pseudobulbar affect; autism; neurological disorders andneurodegenerative diseases, such as, e.g., dementia, amyotrophic lateralsclerosis (ALS, also known as Leu Gehrig's disease), Alzheimer'sdisease, Parkinson's, and multiple sclerosis; disturbances ofconsciousness disorders; brain injuries, such as, e.g., stroke,traumatic brain injury, ischemic event, hypoxic event and neuronaldeath; disturbances of consciousness disorders; cardiovascular diseases,such as, e.g., peripheral vascular diseases, strokes, myocardialinfarctions, and atherosclerosis; glaucoma, tardive dyskinesia; diabeticneuropathy; retinopathic diseases; diseases or disorders caused byhomocysteine-induced apoptosis; diseases or disorders caused by elevatedlevels of homocysteine; chronic pain; intractable pain; neuropathicpain, sympathetically mediated pain, such as, allodynia, hyperpathia,hyperalgesia, dysesthesia, paresthesia, deafferentation pain, andanesthesia delorosa pain; pain associated with gastrointestinaldysfunction, including, e.g., irritable bowel syndrome; mouth pain;epileptic seizures; tinnitus; sexual dysfunction; intractable coughing;dermatitis; addiction disorders, such as, e.g., addiction to ordependence on stimulants, nicotine, morphine, heroine, other opiates,amphetamines, cocaine, and alcohol; Rett syndrome (RTT); voice disordersdue to uncontrolled laryngeal muscle spasms, including e.g., abductorspasmodic dysphonia, adductor spasmodic dysphonia, muscular tensiondysphonia, and vocal tremor; methotrexate neurotoxicity; and fatiguecaused by cancer.

In one particular embodiment, the method of this disclosure is used totreat a subject suffering from or susceptible to a disease or conditionselected from diabetic neuropathy, Rett syndrome (RTT); voice disordersdue to uncontrolled laryngeal muscle spasms, including e.g., abductorspasmodic dysphonia, adductor spasmodic dysphonia, muscular tensiondysphonia, and vocal tremor; methotrexate neurotoxicity; and fatiguecaused by cancer.

In one particular embodiment, the compound of Formula I, wherein R¹ isselected from CH₃, CH₂D, CHD₂, CD₃, CHF₂, and CF₃; and R² is selectedfrom CH₃, CH₂D, CHD₂, and CD₃ or a composition comprising such compoundis used to treat a subject suffering from or susceptible neuropathicpain. In another embodiment, the compound is used to treat a subjectsuffering from pseudobulbar affect.

Methods delineated herein also include those wherein the subject isidentified as in need of a particular stated treatment. Identifying asubject in need of such treatment can be in the judgment of a subject ora health care professional and can be subjective (e.g. opinion) orobjective (e.g. measurable by a test or diagnostic method).

In the methods delineated herein, a pharmaceutical compositioncomprising an effective amount of a compound of Formula I isadministered to a subject, resulting in a plasma exposure level that isgreater than the plasma exposure level of a molar equivalentdextromethorphan composition that is administered using the same dosingregimen. The plasma exposure level is at least 110%, 115%, 120% 125%,130%, 135%, 140%, 145%, or more of the plasma exposure level ofdextromethorphan produced by a molar equivalent dextromethorphancomposition that is administered to an equivalent subject.

In another embodiment, the disclosure provides a method for treating adisease in a subject in need of such treatment, said method comprisingadminstering to the subject a pharmaceutical composition comprising10-60 mg of a compound of Formula I, wherein the administration of thepharmaceutical composition to the subject results in a plasma exposurelevel in the range of 250-750 nanograms (ng)-hour (h)/mL (AUC).

In another embodiment, the disclosure provides a method for treating adisease in a subject in need of such treatment, said method comprisingadministering to the subject a pharmaceutical composition comprising10-60 mg of a compound of Formula I, wherein the administration of thepharmaceutical composition to the subject results in a plasma exposurelevel in the range of 400-1600 ng-h/mL (AUC).

In another embodiment, the disclosure provides a method for treating adisease in a subject in need of such treatment, said method comprisingadministering to the subject a pharmaceutical composition comprising10-60 mg of a compound of Formula I, wherein the administration of thepharmaceutical composition to the subject results in a plasma exposurelevel in the range of 500-1500 ng-h/mL (AUC).

In another embodiment, the disclosure provides a method for treating adisease in a subject in need of such treatment, said method comprisingadministering to the subject a pharmaceutical composition comprising10-60 mg of a compound of Formula I, wherein the administration of thepharmaceutical composition to the subject results in a plasma exposurelevel in the range of 1000-1500 ng-h/mL (AUC).

In another embodiment, the disclosure provides a method for treating adisease in a subject in need of such treatment, said method comprisingadministering to the subject a pharmaceutical composition comprising anamount of a compound of Formula I, effective to decrease in rate andamount of metabolite production as compared to a molar equivalentdextromethorphan composition that is administered using the same dosingregimen.

In another embodiment, the disclosure provides a method for treating adisease in a subject in need of such treatment, said method comprisingadministering to the subject a pharmaceutical composition comprising10-60 mg of a compound of Formula I, the administration of which to asubject results in a plasma exposure level of deuterated dextrorphanisotopologues less than or equal to 1000 ng-h/mL.

In another embodiment, the disclosure provides a method for treating adisease in a subject in need of such treatment, said method comprisingadministering to the subject a pharmaceutical composition comprising10-60 mg of a compound of Formula I, the administration of which to asubject results in a plasma exposure level of deuterated dextrorphanisotopologues less than or equal to 750 ng-h/mL.

In another embodiment, the disclosure provides a method for treating adisease in a subject in need of such treatment, said method comprisingadministering to the subject a pharmaceutical composition comprising10-60 mg of a compound of Formula I, the administration of which to asubject results in a plasma exposure level of deuterated dextrorphanisotopologues less than or equal to 500 ng-h/mL.

In another embodiment, the disclosure provides a method for treating adisease in a subject in need of such treatment, said method comprisingadministering to the subject a pharmaceutical composition comprising10-60 mg of a compound of Formula I, the administration of which to asubject results in both an increase in the plasma exposure level of acompound of Formula I and a decrease in the plasma exposure level ofdextromethorphan metabolite isotopologues, particularly deuterateddextrorphan isotopologues, as compared to the plasma exposure levels ofdextromethorphan and dextrorphan produced from a molar equivalentdextromethorphan composition that is administered in the same dosingregimen.

In another embodiment, the disclosure provides a method for treating adisease in a subject in need of such treatment, said method comprisingadministering to the subject a pharmaceutical composition comprising10-60 mg of a compound of Formula I, said composition providing a plasmaexposure level of a compound of Formula I of from about 1750 to about250 ng-h/mL after repeated administration to a subject every 12 hoursthrough steady-state conditions.

In another embodiment, any of the above methods of treatment comprisesthe further step of co-administering to the subject one or more secondtherapeutic agents. The choice of second therapeutic agent may be madefrom any second therapeutic agent known to be useful forco-administration with dextromethorphan. The choice of secondtherapeutic agent is also dependent upon the particular disease orcondition to be treated. Examples of second therapeutic agents that maybe employed in the methods of this disclosure are those set forth abovefor use in combination compositions comprising a compound of thisdisclosure and a second therapeutic agent.

In particular, the combination therapies of this disclosure includeco-administering to a subject in need thereof a compound of Formula I,wherein R¹ is selected from CH₃, CH₂D, CHD₂, CD₃, CHF₂, and CF₃; and R²is selected from CH₃, CH₂D, CHD₂, and CD₃ or a composition comprisingsuch compound; and quinidine sulfate wherein the subject is sufferingfrom or susceptible to diabetic neuropathy.

In another embodiment the disclosure provides a method of treating asubject suffering from non-small cell lung cancer or malignant pleuralmesothelioma by co-administering to the subject in need thereof acompound of Formula I, wherein R¹ is selected from CH₃, CH₂D, CHD₂, CD₃,CHF₂, and CF₃; and R² is selected from CH₃, CH₂D, CHD₂, and CD₃ or acomposition comprising such compound; and LBH589.

The term “co-administered” as used herein means that the secondtherapeutic agent may be administered together with a compound of thisdisclosure as part of a single dosage form (such as a composition ofthis disclosure comprising a compound of the disclosure and an secondtherapeutic agent as described above) or as separate, multiple dosageforms. Alternatively, the additional agent may be administered prior to,consecutively with, or following the administration of a compound ofthis disclosure. In such combination therapy treatment, both thecompounds of this disclosure and the second therapeutic agent(s) areadministered by conventional methods. The administration of acomposition of this disclosure, comprising both a compound of thedisclosure and a second therapeutic agent, to a subject does notpreclude the separate administration of that same therapeutic agent, anyother second therapeutic agent or any compound of this disclosure tosaid subject at another time during a course of treatment.

Effective amounts of these second therapeutic agents are well known tothose skilled in the art and guidance for dosing may be found in patentsand published patent applications referenced herein, as well as in Wellset al., eds., Pharmacotherapy Handbook, 2nd Edition, Appleton and Lange,Stamford, Conn. (2000); PDR Pharmacopoeia, Tarascon Pocket Pharmacopoeia2000, Deluxe Edition, Tarascon Publishing, Loma Linda, Calif. (2000),and other medical texts. However, it is well within the skilledartisan's purview to determine the second therapeutic agent's optimaleffective-amount range.

In one embodiment of the disclosure, where a second therapeutic agent isadministered to a subject, the effective amount of the compound of thisdisclosure is less than its effective amount would be where the secondtherapeutic agent is not administered. In another embodiment, theeffective amount of the second therapeutic agent is less than itseffective amount would be where the compound of this disclosure is notadministered. In this way, undesired side effects associated with highdoses of either agent may be minimized. Other potential advantages(including without limitation improved dosing regimens and/or reduceddrug cost) will be apparent to those of skill in the art.

In yet another aspect, the disclosure provides the use of a compound ofFormula I alone or together with one or more of the above-describedsecond therapeutic agents in the manufacture of a medicament, either asa single composition or as separate dosage forms, for treatment orprevention in a subject of a disease, disorder or symptom set forthabove. Another aspect of the disclosure is a compound of Formula I foruse in the treatment or prevention in a subject of a disease, disorderor symptom thereof delineated herein.

Thus, in another embodiment, the disclosure provides a method oftreating a disease in a subject in need of such treatment, the methodcomprising co-administering 10-60 mg of a compound of Formula I and2.5-30 mg quinidine, so that the composition provides a maximum plasmaexposure level after repeated administration every 12 to 24 hoursthrough steady-state conditions of a compound of Formula Tin a subjectof from about 1750 to about 250 ng-h/mL, wherein the administration ofsaid composition to a subject results in a reduction in the plasmaexposure level of deuterated dextrorphan isotopologues as compared tothe same molar amount of a compound of Formula I administered withoutthe quinidine.

Thus, in another embodiment, the disclosure provides a method oftreating a disease in a subject in need of such treatment, the methodcomprising co-administering 10-60 mg of a compound of Formula I and2.5-20 mg quinidine, so that the composition provides a maximum plasmaexposure level after repeated administration every 12 to 24 hoursthrough steady-state conditions of a compound of Formula Tin a subjectof from about 1750 to about 250 ng-h/mL, wherein the administration ofsaid composition to a subject results in a reduction in the plasmaexposure level of deuterated dextrorphan isotopologues as compared tothe same molar amount of a compound of Formula I administered withoutthe quinidine.

Thus, in another embodiment, the disclosure provides a method oftreating a disease in a subject in need of such treatment, the methodcomprising co-administering 10-60 mg of a compound of Formula I and2.5-10 mg quinidine, so that the composition provides a maximum plasmaexposure level after repeated administration every 12 to 24 hoursthrough steady-state conditions of a compound of Formula Tin a subjectof from about 1750 to about 250 ng-h/mL, wherein the administration ofsaid composition to a subject results in a reduction in the plasmaexposure level of deuterated dextrorphan isotopologues as compared tothe same molar amount of a compound of Formula I administered withoutthe quinidine.

Thus, in another embodiment, the disclosure provides a method oftreating a disease in a subject in need of such treatment, the methodcomprising co-administering 15-45 mg of a compound of Formula I and2.5-30 mg quinidine, so that the composition provides a maximum plasmaexposure level after repeated administration every 12 to 24 hoursthrough steady-state conditions of a compound of Formula Tin a subjectof from about 1750 to about 250 ng-h/mL, wherein the administration ofsaid composition to a subject results in a reduction in the plasmaexposure level of deuterated dextrorphan isotopologues as compared tothe same molar amount of a compound of Formula I administered withoutthe quinidine.

Thus, in another embodiment, the disclosure provides a method oftreating a disease in a subject in need of such treatment, the methodcomprising co-administering 20-35 mg of a compound of Formula I and2.5-30 mg quinidine, so that the composition provides a maximum plasmaexposure level after repeated administration every 12 to 24 hoursthrough steady-state conditions of a compound of Formula Tin a subjectof from about 1750 to about 250 ng-h/mL, wherein the administration ofsaid composition to a subject results in a reduction in the plasmaexposure level of deuterated dextrorphan isotopologues as compared tothe same molar amount of a compound of Formula I administered withoutthe quinidine.

Thus, in another embodiment, the disclosure provides a method oftreating a disease in a subject in need of such treatment, the methodcomprising co-administering a compound of Formula I and quinidine, sothat the composition provides lower urine concentrations of a compoundof Formula I and higher urine concentrations of deuterated dextrorphanisotopologues in a subject as compared to urine concentrations ofdextromethorphan and dextrorphan in an equivalent subject resulting fromthe administration of a molar equivalent dextromethorphan compositionadditionally comprising the same amount of quinidine and administeredaccording to the same dosing regimen.

Diagnostic Methods and Kits

The compounds and compositions of this disclosure are also useful asreagents in methods for determining the concentration ofdextromethorphan in solution or biological sample such as plasma,examining the metabolism of dextromethorphan and other analyticalstudies.

According to one embodiment, the disclosure provides a method ofdetermining the concentration, in a solution or a biological sample, ofdextromethorphan, comprising the steps of:

a) adding a known concentration of a compound of Formula I to thesolution of biological sample;

b) subjecting the solution or biological sample to a measuring devicethat distinguishes dextromethorphan from a compound of Formula I;

c) calibrating the measuring device to correlate the detected quantityof the compound of Formula I with the known concentration of thecompound of Formula I added to the biological sample or solution; and

d) measuring the quantity of dextromethorphan in the biological samplewith said calibrated measuring device; and

e) determining the concentration of dextromethorphan in the solution ofsample using the correlation between detected quantity and concentrationobtained for a compound of Formula I.

Measuring devices that can distinguish dextromethorphan from thecorresponding compound of Formula I include any measuring device thatcan distinguish between two compounds that differ from one another onlyin isotopic abundance. Exemplary measuring devices include a massspectrometer, NMR spectrometer, or IR spectrometer.

In another embodiment, a method for determining the amount ofdextromethorphan in a solution or a biological sample is provided,comprising:

a) adding a known amount of a compound of Formula I to the solution orbiological sample;

b) detecting at least one signal for a compound of Formula I and atleast one signal for dextromethorphan in a measuring device that iscapable of distinguishing the two compounds;

c) correlating the at least one signal detected for a compound ofFormula I with the known amount of the compound of Formula I added tothe solution or the biological sample; and

d) determining the amount of dextromethorphan in the solution orbiological sample using the correlation between the at least one signaldetected of the compound of Formula I and the amount added to thesolution or biological sample of a compound of Formula I.

In another embodiment, the disclosure provides a method of evaluatingthe metabolic stability of a compound of Formula I comprising the stepsof contacting the compound of Formula I with a metabolizing enzymesource for a period of time and comparing the amount of the compound ofFormula I with the metabolic products of the compound of Formula I afterthe period of time.

In a related embodiment, the disclosure provides a method of evaluatingthe metabolic stability of a compound of Formula I in a subjectfollowing administration of the compound of Formula I. This methodcomprises the steps of obtaining a serum, blood, tissue, urine or fecessample from the subject at a period of time following the administrationof the compound of Formula I to the subject; and comparing the amount ofthe compound of Formula I with the metabolic products of the compound ofFormula I in the serum, blood, tissue, urine or feces sample.

The present disclosure also provides kits for use to treat diabeticneuropathy, Rett syndrome (RTT); voice disorders due to uncontrolledlaryngeal muscle spasms, including e.g., abductor spasmodic dysphonia,adductor spasmodic dysphonia, muscular tension dysphonia, and vocaltremor; methotrexate neurotoxicity; and fatigue caused by cancer. Thesekits comprise (a) a pharmaceutical composition comprising a compound ofFormula I or a salt, hydrate, or solvate thereof, wherein saidpharmaceutical composition is in a container; and (b) instructionsdescribing a method of using the pharmaceutical composition to treatpseudobulbar affect; diabetic neuropathy; Rett syndrome (RTT); voicedisorders due to uncontrolled laryngeal muscle spasms, including e.g.,abductor spasmodic dysphonia, adductor spasmodic dysphonia, musculartension dysphonia, and vocal tremor; methotrexate neurotoxicity; andfatigue caused by cancer.

The container may be any vessel or other sealed or sealable apparatusthat can hold said pharmaceutical composition. Examples include bottles,ampules, divided or multi-chambered holders bottles, wherein eachdivision or chamber comprises a single dose of said composition, adivided foil packet wherein each division comprises a single dose ofsaid composition, or a dispenser that dispenses single doses of saidcomposition. The container can be in any conventional shape or form asknown in the art which is made of a pharmaceutically acceptablematerial, for example a paper or cardboard box, a glass or plasticbottle or jar, a re-sealable bag (for example, to hold a “refill” oftablets for placement into a different container), or a blister packwith individual doses for pressing out of the pack according to atherapeutic schedule. The container employed can depend on the exactdosage form involved, for example a conventional cardboard box would notgenerally be used to hold a liquid suspension. It is feasible that morethan one container can be used together in a single package to market asingle dosage form. For example, tablets may be contained in a bottle,which is in turn contained within a box. In on embodiment, the containeris a blister pack.

The kits of this disclosure may also comprise a device to administer orto measure out a unit dose of the pharmaceutical composition. Suchdevice may include an inhaler if said composition is an inhalablecomposition; a syringe and needle if said composition is an injectablecomposition; a syringe, spoon, pump, or a vessel with or without volumemarkings if said composition is an oral liquid composition; or any othermeasuring or delivery device appropriate to the dosage formulation ofthe composition present in the kit.

In certain embodiment, the kits of this disclosure may comprise in aseparate vessel of container a pharmaceutical composition comprising asecond therapeutic agent, such as one of those listed above for use forco-administration with a compound of this disclosure.

EXAMPLES Example 1 Syntheses of Compounds 100, 101, and 108

Each of the steps and numbered intermediates described below refer tothe corresponding steps and intermediates in Scheme 1, supra.

(+)-3-methoxy-17-methyl-(9α,13α,14α)-morphinan (10b). To a reactionvessel was added (+)-3-methoxy-17-methyl-(9α,13α,14α)-morphinan, HBrsalt (3.00 g, 8.5 mmol), NH₃ in CH₃OH (2.0 M, 8.5 mL, 17.0 mmol), and astir bar. The reaction mixture was stirred at RT for 1 h. The resultingmaterial was concentrated on a rotary evaporator, then diluted withCHCl₃ (50 mL) and H₂O (50 mL). The layers were separated and the waterlayer was extracted with CHCl₃ (50 mL). The combined organic layers weredried over magnesium sulfate, filtered and concentrated on a rotaryevaporator to yield 2.88 g of 10b as a fluffy white solid.

¹H-NMR (300 MHz, CDCl₃): δ 1.12 (ddd, J₁=24.7, J₂=12.6, J₃=3.8, 1H),1.23-1.43 (m, 5H), 1.49-1.52 (m, 1H), 1.62-1.65 (m, 1H), 1.72 (td,J₁=12.6, J₂=4.9, 1H), 1.81 (dt, J₁=12.6, J₂=3.3, 1H), 2.07 (td, J₁=12.6,J₂=3.3, 1H), 2.33-2.47 (m, 5H), 2.57 (dd, J₁=18.1, J₂=5.5, 1H), 2.79(dd, J₁=5.5, J₂=3.3, 1H), 2.98 (d, J=18.1, 1H), 6.68 (dd, J₁=8.2,J₂=2.7, 1H), 6.80 (d, J=2.7 , 1H), 7.02 (d, J=8.8, 1H).

(+)-3-methoxy-(9α,13α,14α)-morphinan (11). The solid 10b (6.79 g, 25.1mmol) was placed in a reaction vessel with CHCl₃ and a stir bar. K₂CO₃(13.85 g, 100.2 mmol) was added and the mixture was stirred at RT underan atmosphere of N₂ for 10 min before the addition of acetyl chloride(7.866 g, 100.2 mmol). The resulting reaction mixture, still under anatmosphere of N₂, was stirred under reflux conditions for 7 h, thenfiltered through a pad of celite. The organic filtrate was concentratedon a rotary evaporator and the resulting crude material was dissolved inCH₃OH then stirred under reflux conditions for 1 h. The solution wasconcentrated on a rotary evaporator then dried under vacuum to yield6.78 g of 11 as an off-white solid.

¹H-NMR (300 MHz, CDCl₃): δ 1.04-1.13 (m, 1H), 1.19-1.29 (m, 1H),1.37-1.66 (m, 6H), 2.37 (d, J=13.5, 2H), 2.54 (bs, 1H), 2.80 (s, 2H),2.95-2.99 (m, 1H), 3.12-3.18 (m, 2H), 3.48 (s, 1H), 3.71 (s, 3H), 6.76(dd, J₁=8.3, J₂=2.6, 1H), 6.80 (d, J=2.3, 1H), 7.07 (d, J=8.3, 1H).

(+)-17-ethylcarbamate-3-methoxy-(9α,13α,14α)-morphinan (12). To areaction vessel fit with a stirbar was added 11 (6.025 g, 2.48 mmol)dissolved in CHCl₃ (100 mL). Diisopropylethylamine (DIEA; 16.32 g, 126.3mmol) was added and the mixture was stirred for 10 min at roomtemperature under nitrogen before the addition of ethylchloroformate(13.094 g, 76.8 mmol). The reaction mixture was stirred under refluxconditions under nitrogen for 3 h, at which point tic (20%ethylacetate/hexane) showed complete consumption of starting material,11. The organic layer was removed and washed first with 1M HCl, and thenwith saturated NaHCO₃. The aqueous layers from each wash were combinedand back extracted with 50 mL of CHCl₃. The organic layer from the backextraction was combined with the organic layer from the washes and thecombined organic layers were dried over NaSO₄. The organic solution wasthen filtered, concentrated on a rotary evaporator then was purified viaautomated flash column chromatography (0-30% ethylacetate/hexane) toyield 5.37 g of 12 as a clear light yellow oil.

¹H-NMR (300 MHz, CDCl₃): δ 1.06 (ddd, J₁=25.3, J₂=12.6, J₃=3.8, 1H),1.21-1.39 (m, 7H), 1.45-1.60 (m, 3H), 1.65-1.70 (m, 2H), 2.34-2.37 (m,1H), 2.54-2.69 (m, 2H), 3.04-3.12 (m, 1H), 3.78 (s, 3H), 3.86 (ddd,J₁=42.3, J₂=13.7, J₃=3.8, 1H), 4.12 (q, J=7.14, 2H), 4.31 (dt, J₁=56.6,J₂=4.3, 1H), 6.71 (dd, J₁=8.8, J₂=2.2, 1H), 6.82 (d, J=2.7 , 1H), 7.00(apparent t, J=8.2, 1H).

(+)-17-ethylcarbamate-3-hydroxy-(9α,13α,14α)-morphinan (13). In areaction vessel fit with a stirbar the carbamate 12 (2.43 g, 7.4 mmol)was dissolved in DCM (20 mL) and the resulting solution was cooled to 0°C. BBr₃ (9.24 g, 36.9 mmol) was added and the reaction mixture wasstirred under an atmosphere of N₂ at 0° C. for 20 min (at which time ticin 20% ethylacetate/hexane showed the reaction to be complete). Asolution of 27% NH₄OH in ice was placed in a beaker with a stir bar andthe reaction mixture was slowly added with stirring. The resultingmixture was stirred for 20 min then was extracted with 4:1 CHCl₃/CH₃OH(200 mL). The organic layer was dried over Na₂SO₄, filtered, thenconcentrated on a rotary evaporator. The crude material was purified viaautomated flash column chromatography (CH₃OH with 1% NH₄OH/CHCl₃,0-10%). The pure fractions were concentrated on a rotary evaporator toyield 1.48 g of 13 as a white solid.

¹H-NMR (300 MHz, CDCl₃): δ 1.04-1.12 (m, 1H), 1.22-1.36 (m, 7H),1.45-1.59 (m, 3H), 1.63-1.67 (m, 2H), 2.30-2.33 (m, 1H), 2.52-2.66 (m,2H), 3.06 (dt, J₁=18.4, J₂=5.9, 1H), 3.84 (ddd, J₁=35.8, J₂=13.8,J₃=6.1, 1H), 4.10-4.18 (m, 2H), 4.31 (dt, J₁=53.9, J₂=3.1, 1H), 6.64 (m,1H), 6.78 (s, 1H), 6.93 (apparent t, J=7.8, 1H).

(+)-17-ethylcarbamate-3-d₃-methoxy-(9α,13α,14α)-morphinan (14; R¹═CD₃).The product 13 (1.48 g, 4.7 mmol) was dissolved in DMF (20 mL) in areaction vessel fit with a stir bar. To this solution was added K₂CO₃(2.97 g, 21.5 mmol). The mixture was stirred under an atmosphere of N₂at RT for 10 min before the addition of CD₃I (1.02 g, 7.0 mmol). Theresulting reaction mixture was stirred overnight at RT at which time tic(20% ethylacetate/hexane) showed complete reaction. The mixture wasdiluted with H₂O then was extracted with ethyl ether (3×30 mL). Thecombined organic layers were dried over Na₂SO₄, filtered, and thefiltrate concentrated on a rotary evaporator to a clear yellow oil.Purification via automated flash column chromatography (0-20%ethylacetate/hexane) and concentration of pure fractions on a rotaryevaporator afforded 793 mg of product.

¹H-NMR (300 MHz, CDCl₃): δ 1.01-1.11 (m, 1H), 1.22-1.39 (m, 7H),1.45-1.59 (m, 3H), 1.62-1.70 (m, 2H), 2.34-2.37 (m, 1H), 2.54-2.69 (m,2H), 3.04-3.12 (m, 1H), 3.84 (ddd, J₁=43.2, J₂=13.8, J₃=4.8, 1H),4.09-4.17 (m, 2H), 4.31 (dt, J₁=56.4, J₂=3.4, 1H), 6.71 (dd, J₁=8.4,J₂=2.5, 1H), 6.82 (d, J=2.7, 1H), 7.00 (apparent t, J=8.2, 1H).

(+)-3-d₃-methoxy-17-d₃-methyl-(9α,13α,14α)-morphinan (Compound 101). Toa reaction vessel fit with a stir bar, was added THF (5 mL) and LAD (100mg, 2.4 mmol). The slurry was cooled to 0° C. followed by the additionof a solution of product 14 (R¹═CD₃, 397 mg, 1.2 mmol) in THF (5 mL).The reaction mixture was stirred under an atmosphere of N₂ for 2 h atwhich time tic (20% ethylacetate/hexane) showed the reaction to becomplete. The mixture was then quenched by the addition of magnesiumsulfate heptahydrate until cessation of gas evolution. Ethyl ether (25mL) was added to the flask, the slurry was filtered, and the organicfiltrate was concentrated on a rotary evaporator to an oil. The crudeproduct was purified via automated flash column chromatography (CH₃OHwith 1% NH₄OH/CHCl₃, 0-10%), concentrated on a rotary evaporator, thendissolved in a saturated solution of HBr in dioxane. The mixture wasstirred for 10 min, was concentrated on a rotary evaporator, then driedunder vacuum for 3 d to yield 204 mg of Compound 101.

¹H-NMR (300 MHz, CDCl₃): δ 1.08 (ddd, J₁=25.1, J₂=12.6, J₃=3.3, 1H),1.22-1.32 (m, 1H), 1.35-1.48 (m, 4H), 1.60 (dd, J₁=39.0, J₂=12.6, 2H),2.02 (dt, J₁=13.2, J₂=4.0, 1H), 2.17 (d, J=11.9, 1H), 2.34 (t, J=13.5,2H), 2.75-2.80 (m, 1H), 2.88 (dd, J₁=18.8, J₂=5.3, 1H), 3.01 (d, J=18.5,1H), 3.15 (s, 1H), 6.73 (d, J=8.6, 1H), 6.81 (s, 1H), 7.05 (d, J=8.6,1H). HPLC (method: 150 mm C18-RP column—gradient method 5-95% ACN;Wavelength: 254 nm): retention time: 6.74 min. MS (M+H⁺): 278.4.

(+)-3-d₃-methoxy-17-methyl-(9α,13α,14α)-morphinan (Compound 100). To areaction vessel fit with a stir bar, was added THF (5 mL) and LAH (91mg, 2.4 mmol). The slurry was cooled to 0° C. followed by the additionof product 14 (R¹═CD₃, 397 mg, 1.2 mmol) dissolved in THF (5 mL). Thereaction mixture was stirred under an atmosphere of N₂ for 2 h at whichtime tic (20% ethylacetate/hexane) showed the reaction to be complete.The mixture was then quenched by the addition of magnesium sulfateheptahydrate until cessation of gas evolution. Ethyl ether (25 mL) wasadded to the flask, the slurry was filtered, and the organic filtratewas concentrated on a rotary evaporator to an oil. The crude product waspurified via automated flash column chromatography (CH₃OH with 1%NH₄OH/CHCl₃, 0-10%), concentrated on a rotary evaporator, then dissolvedin a saturated solution of HBr in dioxane. The mixture was stirred for10 min, was concentrated on a rotary evaporator, then dried under vacuumfor 3 d to yield 200 mg of Compound 100.

¹H-NMR (300 MHz, CDCl₃): δ 1.07-1.16 (m, 1H), 1.22-1.32 (m, 1H),1.34-1.46 (m, 4H), 1.59 (dd, J_(1=41.0,) J_(2=12.6, 2)H), 1.94 (t,J=12.6, 1H), 2.06 (d, J=12.9, 1H), 2.26 (t, J=12.6, 1H), 2.36 (d,J=13.2, 1H), 2.53 (s, 3H), 2.67 (d, J=12.2, 1H), 2.78 (dd, J₁=18.8,J₂=5.0, 1H), 3.06 (d, J=19.2, 2H), 6.72 (d, J=8.3, 1H), 6.81 (s, 1H),7.05 (d, J=8.6, 1H). HPLC (method: 150 mm C18-RP column—gradient method5-95% ACN; Wavelength: 254 nm): retention time: 6.86 min. MS (M+H⁺):275.2.

(+)-3-methoxy-17-d₃-methyl-(9α,13α,14α)-morphinan (Compound 108). To areaction vessel fit with a stir bar, was added THF (2 mL) and LAD (99mg, 2.4 mmol). The slurry was cooled to 0° C. followed by the gradualaddition of carbamate 12(195 mg, 6.0 mmol) dissolved in THF (3 mL). Thereaction mixture was stirred under an atmosphere of N₂ for 10 min atwhich time tic (20% ethylacetate/hexane) showed the reaction to becomplete. The mixture was then quenched by the addition of magnesiumsulfate heptahydrate until cessation of gas evolution. The resultingsolid was washed with ethyl ether, filtered, and the organic filtratewas concentrated on a rotary evaporator to an oil. The crude product waspurified via automated flash column chromatography (CH₃OH with 1%NH₄OH/CHCl₃, 90%), concentrated on a rotary evaporator, and thendissolved in a saturated solution of HBr in dioxane. The mixture wasstirred for 10 min, and then concentrated on a rotary evaporator toyield 74 mg of product.

¹H-NMR (300 MHz, CDCl₃): δ 0.96 (ddd, J₁=25.4, J₂=12.7, J₃=3.9, 1H),1.08-1.18 (m, 1H), 1.24-1.36 (m, 2H), 1.43-1.52 (m, 3H), 1.62 (d,J=12.7, 1H), 1.78 (td, J₁=13.7, J₂=4.4, 1H), 1.96 (d, J=12.2, 1H),2.41-2.47 (m, 2H), 2.97 (dd, J₁=19.5, J₂=5.9, 1H), 3.10-3.18 (m, 2H),3.60-3.63 (m, 1H), 3.73 (s, 3H), 6.81-6.84 (m, 2H), 7.13 (d, J=9.3, 1H),9.60 (bs, 1H). HPLC (method: 150 mm C18-RP column—gradient method 5-95%ACN; Wavelength: 280 nm): retention time: 6.91 min. MS (M+H⁺): 275.7.

Example 2 Microsomal Assays

Certain in vitro liver metabolism studies have been described previouslyin the following references, each of which is incorporated herein intheir entirety: Obach, R S Drug Metab Disp 1999, 27:1350; Houston, J Bet al, Drug Metab Rev 1997, 29:891; Houston, J B Biochem Pharmacol 1994,47:1469; Iwatsubo, T et al, Pharmacol Ther 1997, 73:147; and Lave, T etal, Pharm Res 1997, 14:152.

The objectives of this study were to determine the metabolic stabilityof the test compounds in pooled human and chimpanzee liver microsomalincubations. Samples of the test compounds, exposed to pooled human orchimp liver microsomes, were analyzed using HPLC-MS (or MS/MS)detection. For determining metabolic stability, multiple reactionmonitoring (MRM) was used to measure the disappearance of the testcompounds.

Experimental Procedures: Human liver and Cynomolgus monkey livermicrosomes were obtained from XenoTech, LLC (Lenexa, Kans.). Theincubation mixtures were prepared as follows:

Reaction Mixture Composition

Liver Microsomes 0.5, 1.0 or 2.0 mg/mL NADPH 1 mM Potassium Phosphate,pH 7.4 100 mM Magnesium Chloride 10 mM Test Compound (Dextromethorphan,0.10, 0.25, 1 μM Compound 100, Compound 101, Compound 108)

Incubation of Test Compounds with Liver Microsomes: The reactionmixture, minus cofactors, was prepared. An aliquot of the reactionmixture (without cofactors) was incubated in a shaking water bath at 37°C. for 3 minutes. Another aliquot of the reaction mixture was preparedas the negative control. The test compound was added into both thereaction mixture and the negative control at a final concentration of0.10, 0.25, or 1 μM. An aliquot of the reaction mixture was prepared asa blank control, by the addition of plain organic solvent (no testcompound is added). The reaction was initiated by the addition ofcofactors (not added to the negative controls), and then incubated in ashaking water bath at 37° C. Aliquots (200 μL) were withdrawn intriplicate at multiple time points and combined with 800 μL of ice-cold50/50 acetonitrile/dH₂O to terminate the reaction. The positivecontrols, testosterone and propranolol, as well as dextromethorphan,were each run simultaneously with the test compounds in separatereactions.

All samples were analyzed using LC-MS (or MS/MS). An LC-MRM-MS/MS methodis used for metabolic stability. For testing in cynomolgus monkey livermicrosomes, a final concentration of 1 μM of each compound and 0.5 mg/mLof microsomes were used. FIG. 1 demonstrates that Compound 100 andCompound 101 had greater stability than dextromethorphan in monkey livermicrosomes. The stability of Compound 108 in monkey liver microsomes wassimilar to that of dextromethorphan.

Similar results were obtained using human liver microsomes. FIG. 2demonstrates that approximately 45% of Compound 101 and 42% of Compound100 remained intact after 30 minutes of incubation or 0.25 μM of eachcompound with 2 mg/mL human liver microsomes. In contrast, only about33% of dextromethorphan was still intact after the same period of time.Compound 108 demonstrated similar stability to dextromethorphan.

The relative stability of Compounds 100 and 101 as compared todextromethorphan in human liver microsomes remained the same even at alow (0.1 μM) concentration of compound (data not shown). Decreasing theconcentration of human liver microsomes slows down the metabolism of alltest compounds. After a 30 minute exposure to 0.5 mg/mL approximately75% of Compound 101 and 71% of Compound 100 remained intact.Dextromethorphan showed a higher lability with only about 65% remainingafter the 30 minute incubation.

Example 3 Evaluation of Metabolic Stability in CYP2D6 SUPERSOMES™

Human CYP2D6+P450 Reductase SUPERSOMES™ were purchased from GenTest(Woburn, Mass., USA). A 1.0 mL reaction mixture containing 25 pmole ofSUPERSOMES™, 2.0 mM NADPH, 3.0 mM MgCl, and 0.1 μM of various compoundsof Formula I (Compounds 100, 101, and 108) in 100 mM potassium phosphatebuffer (pH 7.4) was incubated at 37° C. in triplicate. Positive controlscontained 0.1 μM dextromethorphan instead of a compound of Formula I.Negative controls used Control Insect Cell Cytosol (insect cellmicrosomes that lacked any human metabolic enzyme) purchased fromGenTest (Woburn, Mass., USA). Aliquots (50 μL) were removed from eachsample and placed in wells of a multi-well plate at 0, 2, 5, 7, 12, 20,and 30 minutes and to each was added 50 μL of ice cold acetonitrile with3 μM haloperidol as an internal standard to stop the reaction.

Plates containing the removed aliquots were then placed in −20° C.freezer for 15 minutes to cool. After cooling, 100 μL of deionized waterwas added to all wells in the plate. Plates were then spun in thecentrifuge for 10 minutes at 3000 rpm. A portion of the supernatant (100μL) was then removed, placed in a new plate and analyzed using MassSpectrometry.

FIG. 3 shows the results of the Supersomes experiment. Once againCompounds 100 and 101 were much more stable to metabolism thandextromethorphan or Compound 108. Approximately 47% of Compound 101 and40% of Compound 100 remained intact after a 30 minute incubation withthe 2D6 Supersomes™. In contrast, no intact dextromethorphan could bedetected at the 20 minute time point.

The above results all suggest that the presence of deuterium at the R¹position in the compounds of this disclosure imparts greater metabolicstability to the compound as compared to dextromethorphan.

Example 4 Evaluation of Pharmacokinetics of Test Articles C20148, andC10003 in Cynomolgus Monkeys Following Oral Administration inCombination with Quinidine

OBJECTIVE—The objective of this study was to collect plasma samples fromCynomolgus Monkeys at various time points following oral administrationof test articles in combination. The samples were used for thedetermination of plasma drug levels by LC/MS/MS for estimatingpharmacokinetic parameters. This study was conducted in accordance withShanghai Medicilon Inc. Standard Operating Procedures (SOPs). TheSponsor provided the test compounds and internal standard compound.

Animal Husbandry—The animals used were cynomolgus monkeys, who at theage of initiation of treatment, were 3-4 years of age, and weighedbetween 4-6 kg.

Environment and Acclimation—Environmental controls for the animal roomwere set to maintain a temperature of 23±2° C., humidity of 50-70%, anda 12-hour light/12-hour dark cycle. As needed, the 12-hour dark cyclewas temporarily interrupted to accommodate study procedures. Animalswere previously acclimated to study procedures prior to initial doseadministration.

Food and Water—SL-M1 (Shanghai Shilin Biotech Incorporation) wereprovided ad libitum throughout the in-life portion of the study. Waterwas available ad libitum. There were no known contaminants in the foodor water that interfered with this study.

Animal Selection and Fasting—Animals to be used on test were selectedbased on overall health and acclimation to caging. Oral arm was befasted overnight.

Justification—Studies using common mammalian laboratory animals such asmice, rats, dogs, and monkeys are essential and routinely used for theevaluation of the pharmacokinetic characteristics of new chemicalentities. The number of animals in each group is the minimum numberneeded for the assessment of variability between test animals.

EXPERIMENTAL DESIGN—Four Cynomolgus Monkeys were used in this study.

No. of Treatment Animals Dose Level* Dose Conc* Dose Volume Dosing GroupMale Female Test Article (mg/kg) (mg/mL) (mL/kg) Vehicle** Route Collect1 1 0 Dex^(a) 1 each 1each 1 each H2O PO, BID Plasma, &Compound 101compound compound compound (12 H) urine 4 each 4 each compound compoundQuinidine 0   0   1(Vehicle DMI:ETOH:PG blank) 2 1 0 Dex^(a) 1 each 1each 1 H2O PO, BID Plasma, &Compound 101 compound compound (12 H) urineQuinidine 0.5 0.5 1 DMI:ETOH:PG 3 1 0 Dex^(a) 1 each 1 each 1 H2O PO,BID Plasma, &Compound 101 compound compound (12 H) urine Quinidine 1.51.5 1 DMI:ETOH:PG 4 1 0 Dex^(a) 1 each 1 each 1 H2O PO, BID Plasma,&Compound 101 compound compound (12 H) urine Quinidine 6   6   1DMI:ETOH:PG ^(a)“Dex” means dextromethorphan *Each test article will bedissolved at a concentration of 2 mg/mL and dosed at 1 mg/kg **Theformulation will consist of: 10% dimethyl isosorbide, 15% ethanol, 35%propylene glycol (v:v:v) in D5W

Dosing Preparation and Administration—Compound 101 and dextromethorphanwere each dissolved in water up to 2 mg/mL. The combination dose wasprepared by mixing both by 1:1 to yield a concentration of 1 mg/mL foreach compound. The concentration of each compound in the dosing solutionwas re-confirmed by HPLC. Quinidine was prepared in DMI:EtOH:PG:water(10:15:35:40, v/v/v/v) at 3 mg/mL and dosed separately. The doses weregiven BID orally with an interval of 12 hours. Dosing volume of thedextromethorphan/Compound 100 mixture was 1 mL/kg. Dosing volume ofQuinidine was determined based on the dose each animal was getting. Dosevolumes for each test animal was determined based on individual bodyweight. Body weights were taken on each day of dose administration andwere be recorded.

Blood Sample Collection—Blood sampling took place on Day 6 after oraladministration of the last dose (Dose 11). Blood (approximately 1 mL)was collected via femoral vein into tubes containing sodium heparinanticoagulant at 0.25, 0.5, 1, 1.5, 2, 3.5, 6 and 8 hours. The plasmawas separated via centrifugation and stored in −20° C. before analysis.

Urine Sample Collection—Urine samples in between two doses on Day 5 (for12 hours between doses 9 and 10) were collected in a plate andquantified by volume. After collection, the urine samples were be storedin −20° C. and then shipped back to client.

Acceptable Time Ranges—Blood samples for each time point were collectedwithin 10% for the time points before the first hour and within ±5minutes for the time points after 1 hour.

Sample Handling and Storage—Blood was stored on ice, or at approximately5° C. prior to centrifugation to obtain plasma samples. Centrifugationtook place within 30 minutes of blood collection to harvest plasma(maximum volume). Plasma samples were stored on dry ice or atapproximately −20° C. until analysis.

Antemortem Observations—During dosing and at the times of bloodcollections, animals were observed for any clinically relevantabnormalities including food consumption, weight, injection position,activity, or feces and urine, for example.

Sample Analysis—Analyses of plasma samples was conducted by theBioanalytical Group of Medicilon/MPI Inc. The concentrations of bothparent compounds (dextromethorphan and Compound 100) and 2 metabolites(Dextrorphan and Dextrorphan-D3) in plasma & urine were determined usinga high performance liquid chromatography/mass spectrometry (HPLC/MS/MSAPI 3000) method. Dilution using cynomolgus monkey plasma blank wereapplied if the sample concentration was over the ULOQ of calibrationstandard curve. The data acquisition and control system was createdusing Analyst 1.4 software from ABI Inc.

The results are summarized in FIGS. 4, 5, and 6. FIG. 4 depicts theplasma levels of Compound 101 and deuterated dextrorophan compared todextromethorphan and dextrorphan without quinidine co-administration.FIG. 4 demonstrates that higher plasma concentration levels of Compound101 are observed compared to dextromethorphan when Compound 101 anddextromethophan are administered to monkeys at the same dose (4 mg).FIG. 4 also shows that metabolism of Compound 101 to deuterateddextrorphan isotopologues is reduced relative to metabolism ofdextromethorphan to dextrorphan. As indicated in the Background sectionof this application, the abuse potential of dextromethorphan are morereliably attributable to dextrorphan, and abuse potential in humans ofdextromethorphan metabolism to dextromethorphan. FIG. 4 thus suggeststhat the compounds of the disclosure may be useful in reducingmetabolism of dextromethorphan isotopologues to dextrorphanisotopologues, and thus in reducing the abuse potential of suchcompounds.

FIG. 5 summarizes codosing data. The results indicate that Compound 101plasma levels are greater than dextromethorphan plasma levels when eachcompound is co administered with the same amount of quindine. Therelative effect of increasing quinidiine dose has a greater effect onthe plasma level of Compound 101 than it has on dextromethorphan.

FIG. 6 depicts urine levels of Compound 101, and dextromethorphan, aswell as deuterated dextrorphan isotopologues and dextrorphan as afunction of quinidine concentration in monkeys. Compound 101 anddextromethorphan levels are affected by increasing quinidineconcentration. At the same quinidine concentration, there is lessCompound 101 in the urine than dextromethorphan. Quinidine concentrationalso affects metabolite levels in the urine. The data indicate thatthere is less deuterated dextrorphan isotopologues than dextrorphan inthe urine for a given quinidine concentration.

Example 5 Radioligand Assay Data Measuring Binding of Compounds to NMDA(PCP) and the Sigma-1 Receptor

The assays were run by MDS Pharma Services according to the followingreferences, the contents of which are incorporated herein: Siegel B W,Sreekrishna K and Baron B M (1996) Binding of the radiolabeled glycinesite antagonist [3H]MDS105,519 to homomeric NMDA-NR1a receptors. Eur JPharmacol. 312(3):357-365; Goldman M E, Jacobson A E, Rice K C and PaulS M (1985); and Differentiation of [.H] phencyclidine and(+)-[.H]SKF-10047 binding sites in rat cerebral cortex. FEB S Lett.190:333-336. Ganapathy M E, Prasad P D, Huang W, Seth P, Leibach F H andGanapathy V (1999) Molecular and ligand-binding characterization of thes-receptor in the Jurkat human T lymphocyte cell line. J Pharmacol ExpTher. 289: 251-260.

Assay Methods:

Glutamate, NMDA, Glycine Source: Wistar rat cerebral cortex Ligand: 0.33nM [3H] MDL-105519 Vehicle: 1% DMSO Incubation Time/Temp: 30 minutes @4° C. Incubation Buffer: 50 mM HEPES, pH 7.7 Non-specific Ligand: 10 μMMDL-105519 KD: 6 nM * BMAX: 3.7 pmole/mg Protein* Specific Binding:85% * Quantitation Method: Radioligand Binding Significance Criteria:≧50% of max stimulation or inhibition Glutamate, NMDA, PhencyclidineSource: Wistar rat cerebral cortex Ligand: 4 nM [³H] TCP Vehicle: 1%DMSO Incubation Time/Temp: 45 minutes @ 25° C. Incubation Buffer: 10 mMTris-HCl, pH 7.4 Non-specific Ligand: 1 μM Dizolcipine ((+)-MK-801) KD:8.4 nM * BMAX: 0.78 pmole/mg Protein* Specific Binding: 94% *Quantitation Method: Radioligand Binding Significance Criteria: ≧50% ofmax stimulation or inhibition Sigma σ1 Source: Human Jurkat cellsLigand: 8 nM [³H] Haloperidol Vehicle: 1% DMSO Incubation Time/Temp: 4hours @ 25° C. Incubation Buffer: 5 mM Potassium Phosphate, pH 7.5Non-specific Ligand: 10 μM Haloperidol KD: 5.8 nM * BMAX: 0.71 pmole/mgProtein* Specific Binding: 80% * Quantitation Method: RadioligandBinding Significance Criteria: ≧50% of max stimulation or inhibition *Historical Value

Results.

The binding results are summarized in the following table for Compound101 compared to dextromethorphan.

Dextromethorphan Compound 101 NMDA (PCP) 2.79 ± 0.39 μM 3.46 ± 0.34 μMSigma σ1 3.55 ± 0.19 μM 2.02 ± 0.24 μM

Without further description, it is believed that one of ordinary skillin the art can, using the preceding description and the illustrativeexamples, make and utilize the compounds of the present disclosure andpractice the claimed methods. It should be understood that the foregoingdiscussion and examples merely present a detailed description of certainpreferred embodiments. It will be apparent to those of ordinary skill inthe art that various modifications and equivalents can be made withoutdeparting from the spirit and scope of the disclosure. All the patents,journal articles and other documents discussed or cited above are hereinincorporated by reference.

1.-21. (canceled)
 22. A method of evaluating the metabolic stability ofa deuterated morphinan compound, comprising: a. contacting a firstamount of the deuterated morphinan compound with a metabolizing enzymesource for a period of time sufficient to allow the formation of amixture comprising one or more metabolic products of the deuteratedmorphinan compound and a remaining amount of the deuterated morphinancompound; b. at the period of time, determining the remaining amount ofthe deuterated morphinan compound and the amount of at least one of theone or more metabolic products in the mixture; and c. comparing theremaining amount of the deuterated morphinan compound determined in stepb. with the first amount of the deuterated morphinan compound and/orcomparing the first amount of the deuterated morphinan compound with theamount of the at least one of the one or more metabolic productsdetermined in step b. to determine the metabolic stability of thedeuterated morphinan compound, wherein the metabolic stability isexpressed as the % of the amount of the deuterated morphinan compounddetermined in step b. relative to the first amount and/or as the % ofthe at least one of the one or more metabolic products determined instep b. relative to the first amount of the deuterated morphinancompound.
 23. The method of claim 22, wherein the deuterated morphinancompound is a compound of Formula I

or a pharmaceutically acceptable salt thereof, wherein: R¹ is selectedfrom CH₃, CH₂D, CHD₂, CD₃, CHF₂, and CF₃; and R² is selected from CH₃,CH₂D, CHD₂, and CD₃; provided that at least one of R¹ or R² is CH₂D,CHD₂, or CD₃.
 24. The method of claim 22, wherein the metabolizingenzyme source comprises liver microsomes.
 25. The method of claim 24,wherein the liver microsomes are pooled human liver microsomes or pooledchimpanzee liver microsomes.
 26. The method of claim 22, wherein thedetecting is performed by high performance liquid chromatography-massspectrometry (HPLC-MS), mass spectrometry/mass spectrometry (MS/MS),multiple reaction monitoring (MRM), or combinations thereof.
 27. Themethod of claim 22, wherein the method is performed in vitro.
 28. Themethod of claim 22, wherein the period of time is at least 2, 5, 7, 12,20, or 30 minutes.
 29. The method of claim 22, wherein the period oftime is about 2, 5, 7, 12, 20, or 30 minutes.
 30. The method of claim22, wherein the deuterated morphinan compound has greater metabolicstability as compared to non-deuterated dextromethorphan assessed usingthe same method.
 31. The method of claim 22, further comprising: d.comparing the metabolic stability of the deuterated morphinan compoundto the metabolic stability of a non-deuterated analog of the morphinancompound assessed using the same method.
 32. A method of evaluating themetabolic stability of a deuterated morphinan compound in a subject,comprising: a. administering a first amount of the deuterated morphinancompound to a subject; b. obtaining a serum, blood, tissue, urine, orfeces sample from the subject at a period of time following theadministration of the compound to the subject, wherein the period oftime is sufficient to allow the formation of one or more metabolicproducts of the deuterated morphinan compound in the sample; c. at theperiod of time, determining the remaining amount of the deuteratedmorphinan compound and the amount of at least one of the one or moremetabolic products in the sample; and d. comparing the remaining amountof the deuterated morphinan compound determined in step b. in the samplewith the first amount of the deuterated morphinan compound and/orcomparing the first amount of the deuterated morphinan compound with theamount of the at least one of the one or more metabolic productsdetermined in step b. in the sample to determine the metabolic stabilityof the deuterated morphinan compound, wherein the metabolic stability isexpressed as the % of the remaining amount of the deuterated morphinancompound determined in step b. relative to the first amount and/or asthe % of the at least one of the one or more metabolic productsdetermined in step b. relative to the first amount of the deuteratedmorphinan compound.
 33. The method of claim 32, wherein the deuteratedmorphinan compound is a compound of Formula I

or a pharmaceutically acceptable salt thereof, wherein: R¹ is selectedfrom CH₃, CH₂D, CHD₂, CD₃, CHF₂, and CF₃; and R² is selected from CH₃,CH₂D, CHD₂, and CD₃; provided that at least one of R¹ or R² is CH₂D,CHD₂, or CD₃.
 34. The method of claim 32, wherein the detecting isperformed by high performance liquid chromatography-mass spectrometry(HPLC-MS), mass spectrometry/mass spectrometry (MS/MS), multiplereaction monitoring (MRM), or combinations thereof.
 35. The method ofclaim 32, wherein the period of time is at least 0.5, 1, 1.5, 2, 4, 8 or12 hours.
 36. The method of claim 32, wherein the period of time isabout 0.5, 1, 1.5, 2, 4, 8 or 12 hours.
 37. The method of claim 32,wherein the subject is a human.
 38. The method of claim 32, wherein thedeuterated morphinan compound has greater metabolic stability ascompared to non-deuterated dextromethorphan assessed using the samemethod.
 39. The method of claim 32, further comprising: e. comparing themetabolic stability of the deuterated morphinan compound to themetabolic stability of a non-deuterated analog of the morphinan compoundassessed using the same method.